Currently, helium in gas form is used in a large number of different industrial sectors, in particular in the electronics industry, for cooling silicon wafers, or inerting printed circuits, for example, or in the glass industry, for example for cooling optical fibres during their fabrication process.
Conventionally, the helium is first delivered in liquid form in a large quantity to a transfer and re-storage station, in which the helium is vaporized then compressed before being forwarded to the site where it is used by being stored either in gas cylinders or similar containers whose size may vary but whose capacity is never more than a few hundreds of litres. This is, moreover, summarized in document U.S. Pat. No. 5,386,707 (Col. 1, 1. 30-35).
Furthermore, in certain cases, the liquid helium is directly conveyed to the site where it is used in a low-capacity storage reservoir, generally in a reservoir having a volume of less than 3000 litres, where it can be stocked before being conveyed in gas form to a utilization site.
In this case, when the utilization site contains a plurality of production lines, each using large amounts of helium gas, the amounts used varying from one line to another, it is essential to provide as many helium-gas reservoirs as there are production lines, that is to say each production line needs to be connected, by means of an individual duct, to a helium reservoir which is specific to it, for example helium cylinders, so that each of the production lines can be fed independently of the others as a function of the helium requirements of the line in question.
Such devices are in particular described in documents U.S. Pat. No. 5,386,707, U.S. Pat. No. 4,607,490, U.S. Pat. No. 4,766,731, U.S. Pat. No. 3,415,069, U.S. Pat. No. 4,972,677, U.S. Pat. No. 4,444,572 and JP-A-6241654.
However, these known plant types have several drawbacks, namely:
the fact that it is necessary to re-store the liquid helium in helium gas form in a transfer station causes a considerable increase in the costs of transporting and storing the fluid; PA1 when the liquid helium is delivered to the utilization site in the form of pressurized containers, it is necessary to replace the containers all the more frequently when the amount of helium which they contain is small; PA1 when each production line is connected to its own helium reservoir, the complexity of the plant is increased considerably through an increase in the number of equipment items which therefore, here again, increases the overall cost of the subsequent fabrication process. PA1 a helium source having an internal volume of at least 7000 litres, PA1 a network of a plurality of secondary ducts, each feeding at least one production line using helium gas, PA1 a main duct for conveying helium, connected upstream to the helium source and downstream to the network of secondary ducts feeding the production lines, each production line being fed with helium output by the helium source having an internal volume, that is to say a capacity in excess of 7000 litres. PA1 the helium source has an internal volume of at least 8000 litres, preferably at least 15,000 litres, more preferably of at least 20,000 litres, more preferably at least 40,000 to 50,000 litres; PA1 the helium source is mobile, such as a road tanker or a railway tanker, or static, such as a storage vessel or a buffer tank; PA1 the main duct is furthermore connected to at least one device selected from the group formed by a heat exchanger, a buffer tank, helium purification means, and/or compression means; PA1 it furthermore has means for controlling the flow rate and/or the pressure of helium gas in the main duct and/or in each of the secondary ducts of the network; PA1 the production lines are selected from the group formed by: PA1 the production lines are connected, independently of one another, to the main duct by means of the network, PA1 the helium drawn from the helium source is in gas, liquid or supercritical form, preferably in liquid or supercritical form. PA1 a main duct is fed with helium drawn from a helium source having an internal volume of at least 7000 litres, preferably of at least about 10,000 litres, PA1 the helium is conveyed in the main duct to a network of a plurality of secondary ducts, each feeding at least one production line using helium gas, PA1 each of the production lines is fed with helium in gas form originating from the helium source. PA1 the helium is drawn from the helium source in liquid or supercritical form and, after being drawn off, is subjected to at least one vaporization step so as to obtain helium gas, PA1 the pressure and/or the flow rate of helium in the main duct is adjusted as a function of the sum of the pressures and/or of the flow rates of helium gas in each of the secondary ducts.